Art of making gears



M TIBBETTS ART or MAKING GEARS.

APPLICATION FILED'NOV. 22, 1915. I

Patented Apr. 13, 1920..

from 'i which it,A is made. 5,5

-motor vehicle transmission boxes -F ig. 1 may fbe forged into `shown in Fig. 2; and f.,

'UNITED STATES PATENT OFFICE.

MILTON TIBBETTS, 0F DETROIT, MICHIGAN, ASSIGNOR TO PACKARD MOTOR CAR COMPANY, OF DETROIT, MICHIGAN, A CORPORATION OF MICHIGAN.

.ART OF MAKING GEARS.

Specification of Letters Patent.

Patented Apr. 13, 1920.

Application filed November 22, 1915. Serial No. 62,797'.

T 0 all whom it may concern:

Be it known that ll,- MILTON Tinrrs, a

citizen of the United States, and resident of Detroit, Wayne county, State of Michigan, have invented certain new and useful Improvements in the Art of Making Gears, of which the following'is a specification.

' This invention relates to gears and the method of making gears and particularly gears having rounded or chamfered tooth ends. l

Spur gears as used in sliding gearing, in

for instance, are usually chamfered at one or both ends ofthe teeth for the purpose of facilitating the sliding of the, gears into mesh. Heretofore, this chamfering or rounding of the tooth ends has been, donev by a suitable cutting tool after the gear teeth have been cut. It is one of the salient objectsof this invention to dispense with the necessity of this cutting operation to obtain the cham- .fered teeth, and in carrying out -the invention the gear blank is subjected to a pressing or forging operation by a tool which serrates one or both of the peripheral edges of the blank and the tooth spaces are then cut inthe blank to coincide with the serra-tions.

Other objects will appear from the following description, taken in connection with the drawings Whichl form a part of the specification and in which:

Figure 1 is an elevation `and. part sectional view of the blank kof raw material out of which the gear-is formed;

Fig. 2 is a similanview of the gear blank after the forging andpserrating operation; Fig. 3 is asimilar View of the gear blank after being machined," l

F'g. 4 is a similar view of the finished geen Fig. 5 is a plan View of a gear blank showing the serrations formed by stamping and also the completed teeth after the cutting operation;

Fig. 6 shows a forging or stamping machine by which the raw material shown in the gear blank Fig. 7 shows a toothrcutting machine by which thegea'r kmay be completed.

Referring'to thedrawings, B, throughout the figures, represents the gear or the blank In* Fig. 1 it is simply a. disk of iron or steel, or other metal` -of the desired composition. In Fig. 2, the

- the blank.

In Fig. 3 the surplus metal of the blank has been removed by machining, a groove 1a being formed in the boss 10 to receive the usual yoke for shifting the gear axially.

In Fig. 4 the teeth 15 have been cut in the rim portion 12 of the gear blank, the spaces between the gear teeth corresponding to the depressions 16 shown in Figs. 2 and 5 between the projections 13. Thus the ends of each of the teeth 15 in the finished gear shown in Fig. 4 and at the right in Fig. 5, are rounded 0E or chamfered, for the purposes described above.

For performing the various operations on the gear blanks, well known machines of the types illustrated in Figs. 6 and 7 may be used. In Fig. 6, a forging or stamping Ymachine is shown at 17, and it comprises a stationary bed 18 upon which is mounted a die 19, and a movable bed 20 to which is secured a die 21. The movable bed or block 20 may be reciprocated toward the stationary bed 18 by a piston arranged in a suitable cylinder 22, to which steam or other pressure may be supplied as by a pipe 23.

The blankl, shown in Fig. 1 of the drawings may be forged or pressed into the shape in which it is shown in Fig. 2 and as resting in the die 19 in Fig. 6, by one or a series of forging or pressing operations. @ne or a series of roughing dies may first be used to approximate the shape shown in Fig. 2 and the final pressing or forging operation may use the finishing dies, such as shown in Fig. 6 at 19 and 21, so that the blank B is ready for machining, the projections 13 having been formed in the rim portion 12 of the blank. -f

For the purposes of this application, it hardly seems necessary to illustrate a machine for removing the surplus metal to bring the blank to the form shown in Fig. 3 as any well known lathe may beused. v

In Fig. 7 is illustrated a machine for cutting the spaces between the teeth. This machine 24 comprises principally a rotating v and reciprocating cutting tool 25, which cuts the tooth spaces in register With the dechamfered ends".

One mode only of carrying out the steps of the method is shown but it is apparent that the invention is not limited thereby and that other modes could be used Without departing from the spirit or scope of the invention as set forth .in the claims.

Having thus described my invention, What I claim and desire to secure by Letters Pat- 1. A method of making toothed gears consisting in first forming rounded tooth ends on the blank by a pressing operation, and then forming the remainder of each tooth by a cutting operation.

2. A method of making toothed gears consisting in irst forming: all of the ,tooth ends on the blank and shaping lsaid ends differently from the material of the blank between them and then forming the tooth spaces between said ends. f i

3. A method of making toothed'gears consisting in first forming all of the tooth ends on the blank and shaping said ends difierently from the material of the blank between them and then forming the tooth spaces be- 6. A method of making toothed gears con-v sisting inwirst forming rounded tooth ends on the blank, and then cutting the remainder of the teeth.

7. A method of making gears consisting of forminga gear blank With serrations in one of its peripheral edges, and then cutting the tooth spaces to coincide with the serrations. f

8. A method of making gears consisting of forming and indicating the tooth ends on 'the blank by pressing, and forming the remainder of each tooth by a cutting operation corresponding to the tooth end indications. i y

In testimony Whereofl afiiX my signature.

MILTON TIBBETTS. 

